Hazardous and expensive gases are used in many manufacturing systems. For example, gases such as hydrogen, helium, oxygen, fluorine, nitrogen, carbon monoxide, nitrous oxide, hydrogen fluoride, arsenic hexafluoride, and the like are used as process gases in a variety of manufacturing situations, for example, etching or chemical vapor deposition in semiconductor processing, gas metal arc welding, chemical manufacturing, petroleum refining, thermal spray coating, and the like. A significant problem is delivering these gases to applications in a manufacturing environment while detecting and mitigating leaks. Even small amounts of leakage can be hazardous, for example, the explosive limit for hydrogen gas at standard temperature and pressure is about 4% by volume.
There are a number of commercially available gas detectors that can be configured for a variety of gases, but they are costly, particularly if contemplated for use with a gas supply system that is spread over a large area. Also, these detectors provide leak detection only after a detectable amount of gas has leaked and contacted the detector, which can be a significant amount of gas depending on the location of the detector and surrounding air currents. Furthermore, a catastrophic leak may not be detected until a significant amount of gas has been released, for example, if a high-pressure gas delivery line is accidentally severed. In a large system, this can create a safety hazard and waste a significant amount of gas before detection. In response, the sensitivity of the detector can be increased, however, this leads to an increased number of false alarms, which can cause costly downtime and desensitize personnel to real alarms.
An example of a hydrogen supply system exists for supplying hydrogen to a thermal spray application. However, the system only detects a leak after a significant amount of flammable hydrogen gas has already leaked from the system. The system is controlled by a hard-wired relay control system and cannot be easily reconfigured for different process conditions or improved safety protocols. Additionally, the system does not provide redundancy for safety in case of failure of critical components, nor does it provide for automatic calibration and monitoring of critical sensor components. Furthermore, the system can be used with only one application at a time.
Therefore, there is a need in the art for a system and method to supply process gases, in particular hydrogen, to one or more applications in a manufacturing facility. The system must have multiple levels of redundancy for safety and must automate multiple leak detection methods, while at the same time minimizing false alarms. The system must provide for rapid detection and mitigation of catastrophic leaks.